This disclosure relates to compression of borehole images obtained by a downhole tool.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions.
A variety of downhole tools may collect information about a borehole drilled into a geological formation. Some downhole tools may obtain information about the geological formation in a format that may be referred to as “borehole images.” A variety of tools may obtain borehole images, including resistivity tools, acoustic tools, and caliper tools, to name a few. The borehole images may be used for well placement, borehole integrity monitoring, and many other drilling and measurement circumstances. As such, it may be desirable that good quality images be available at the surface even while the downhole tool is logging the borehole.
Although it may be desirable to obtain the results of the borehole imaging substantially in real time while the downhole tool is logging the borehole, the telemetry link between the downhole tool and the surface may have limited communication bandwidth. Indeed, the bandwidth of both mud pulse telemetry and electromagnetic telemetry may be very limited, and even with higher-bandwidth telemetry such as Wired Drill Pipe, it may be desirable to use the data rate as efficiently as possible. As such, the borehole images may be compressed before being transferred to the surface. The state of the art in image compression, however, is generally specialized for natural images (e.g., JPEG compression). Image compression associated with natural images is used on borehole images, but the resulting compressed images may still exceed a desired data transfer size and/or cannot efficiently represent features relevant to borehole imaging. Moreover, compression associated with natural images may have performance that is impacted by the small number of azimuthal samples that may be found in a borehole image (e.g., 80 bins in some cases). Using such image compression may therefore limit the amount of borehole imagery that may be provided to the surface while the downhole tool is logging the borehole.